This is an elegant dessert for a shower or a sweets buffet. For a special presentation, each one is topped with a dove made of white chocolate.
Prepare an ice-water bath; set aside. In a small bowl, sprinkle gelatin over 6 tablespoons water; let soften, 10 minutes.
Bring cream and sugar to a simmer in a medium saucepan over medium heat. Add gelatin mixture; cook, stirring, until gelatin and sugar are dissolved, 2 minutes.
Transfer mixture to a large glass bowl set in the ice-water bath; whisk until cool, 6 to 7 minutes. Stir in extract. Divide mixture evenly among 12 (6-ounce) ramekins. Refrigerate until set, at least 2 hours.
Melt white chocolate, stirring, in a heatproof bowl set over a pan of simmering water. Spoon chocolate into 12 (1 1/2-by-1-inch) dove-shaped candy molds. Lightly tap molds against a flat surface to smooth tops. Freeze until set, about 20 minutes. Unmold onto parchment paper.
Place ramekins in a shallow roasting pan filled with 1 inch of warm water for 1 minute, being careful not to let water reach the top of ramekins. Run a knife around edges of each ramekin to loosen panna cotta; invert onto serving plates, shaking plate and ramekin until panna cotta slides out. Place a white-chocolate dove in the center of each panna cotta.